Sports is littered with great athletes who’ve had wonderful careers but never got to wear a championship ring. Last night Jason Giambi did his part to get out of that dubious crowd.

In a shocking pre-Game 7 stunner, Yankees manager Joe Torre dropped Giambi from third to seventh in the lineup because he’s been mired in a postseason slump. It worked. Giambi broke out against one of the best pitchers in baseball, blasting two home runs.

For seven-plus innings, Giambi was the only offense the Yankees had against Pedro Martinez. He blasted two solo home runs off Martinez, one in the fifth, the other in the seventh. When Aaron Boone blasted a game-winning home run in the 11th to give the Yankees a 6-5 win, Giambi’s dream for a ring remained alive.

“This is the greatest moment of my life,” Giambi said. “I came here to play in a World Series and I am.”

It was an anxious and gut-wrenching night for Giambi from start to finish.

The water-main break that closed the George Washington Bridge and wreaked havoc with traffic, left Giambi to place a frantic call to the Yankees’ offices, saying he was stuck in gridlock. Giambi was told to look for police and he spotted a van at 145th Street.

Behind an escort of flashing lights and cops from the 32nd Precinct, Giambi pulled his Porsche into the players’ lot at 5:48, 48 minutes late.

Giambi, who likely will need knee surgery after the season, had been unable to pull out of his slump in the postseason. He went into Game 7 hitting just .190 in the series. And on the mound for the Red Sox last night was their ace, Martinez.

Torre explained that he dropped Giambi in the order because he was struggling and he had not had success against Martinez. But Giambi does have good numbers batting in the No.7 spot. The last time he did so (July 7, 1999 with Oakland), Giambi went 1-for-4 with a home run and four RBIs.

“I don’t know how to explain it,” Giambi said. “Joe talked to me before the game and I was fine with it. It’s not about me. It’s about the team. I was very relaxed when I was at the plate.”

Outwardly, Giambi took all this in stride, just as he did the bumper-to-bumper traffic that had him stuck at 145th Street. “It wasn’t moving,” Giambi said of the traffic. “There were all kinds of accidents because everyone was so [upset] about the traffic. They were cutting each other off.”

When Giambi finally took the field for batting practice, his teammates already had done their stretching.